1. Field of the Invention
The present invention relates to a solid-state imaging apparatus, and more particularly to a solid-state imaging apparatus characterized by including an AD converting circuit in each column to perform arithmetic processing to an obtained plurality of digital signals and a method of driving the solid-state imaging apparatus.
2. Description of the Related Art
The so-called horizontal skipped reading (hereinafter regarded as the same meaning as horizontal skipping operation) has been known in a conventional solid-state imaging apparatus. In the horizontal skipped reading, for example, an analog electric signal, obtained by converting an incident light in each pixel, is read out in every other column of the pixels arranged in a matrix in a use of requiring a high speed operation, such as in a moving image.
Moreover, Japanese Patent Application Laid-Open No. 2006-025189 discloses that an AD converting circuit is provided to each column of pixels, and that a digitized signal is arithmetically processed. To put it concretely, the patent application describes an image sensor provided with two register circuits in each pixel column to store two different signal levels in the same pixel into the register circuits, which image sensor operates the difference between both of the signal levels in a digital region after the storage of the signal levels.
If a horizontal skipping operation is performed and operations are performed on the basis of the signals held in the plurality of respective register circuits in the circuit configuration disclosed in the aforesaid Japanese Patent Application Laid-Open No. 2006-025189, then the AD converters and register circuits in the skipped, that is, not read out, columns become the state of not participating in the operations. This state leaves room for an examination pertaining to the aspect of the utilization efficiency of the circuits.